Water temp affects on test results

[Gordo33]

I just finished testing my pond and was surprised to see a TDS reading 59ppm. The cause for my surprise is my discus aquarium which has a 6x/ hr turn over rate is 269ppm ( 12 hrs after a 50% water change). The aquarium is 84 degrees F while the pond is 44 degrees F.

So I did a non scientific experiment with my tap water. Water cold to my touch had aTDS reading 193ppm and warm to touch was 234ppm. I repeated this several times and found a similar difference each time.

I was using this probe

Does anyone know if water temp would also affect the readings for API fresh water test kit?

 

[sissy]

I have found that in my pond that is why I take water out and bring it in the house and let it sit until it gets to room temp .I have the API liquid test kit and found that out at least 8 years ago .I tested cold water in the winter a couple of times at readings i knew could not be right .So i used a jar that I cleaned really well and brought the pond water in and left it sit for an hour with just a piece of plastic wrap covering the top so nothing would get in .I have a meter also and it never has read right in colder water .I just figured it was me since no one ever brought up there tests in winter .I do think I may have mentioned it though

 

[Meyer Jordan]

What brand is your probe? The better probes are self-calibrating, is this one?

 

[Gordo33]

What brand is your probe? The better probes are self-calibrating, is this one?

by Generic
LCD Digital TDS Meter Tester Water Quality Ppm Purity
Cheap one purchased on Amazon a couple years ago. Less than $10 doubt it self calibrates. I no longer have paper work on it. Checked my orders on Amazon to find this. Doesn't mention calibrating for temp.

 

[Gordo33]

I have found that in my pond that is why I take water out and bring it in the house and let it sit until it gets to room temp .I have the API liquid test kit and found that out at least 8 years ago .I tested cold water in the winter a couple of times at readings i knew could not be right .So i used a jar that I cleaned really well and brought the pond water in and left it sit for an hour with just a piece of plastic wrap covering the top so nothing would get in .I have a meter also and it never has read right in colder water .I just figured it was me since no one ever brought up there tests in winter .I do think I may have mentioned it though

That is interesting your API liquid test kit was different with cold water. My winter readings were the same as summer and fall. I know the kit is working because I just used to cycle an aquarium.

 

[Gordo33]

@Meyer Jordon, what is TDS showing? What reading is considered normal for the pond? Can a inference be made to the DOC level based on TDS value?
Thanks

 

[sissy]

Mine is a new test kit I got in November .When I left the water warm up a little the test came out fine each time and my old test kit read the same way .I even got worried about the water .Before I put in the new pond I did not test my water as much and did not even test it in the winter because it seemed well established .Same kit I always buy .I am going to check it tomorrow because I usually do it on monadys and was busy building stuff today .Can't wait to put all my new stuff out .

 

[Meyer Jordan]

@Meyer Jordon, what is TDS showing? What reading is considered normal for the pond? Can a inference be made to the DOC level based on TDS value?
Thanks

TDS (Total Dissolved Solids) is the level of mainly inorganic elements that are in dissolution in water in an ionic state (salts). Nitrate is one such salt. Some organics may be present. Measuring TDS is actually measuring conductance. Levels <500 are considered normal for fresh water. And YES, temperature does affect this conductivity with lower readings occurring as water temperature drops.
DOC (Dissolved Organic Carbon) is comprised of various organic molecules.
There is no binding relation between the two (2). Each is independent of the other.